1. Field of the Invention
The present invention relates to resettable circuit interrupting devices and systems which includes ground fault circuit interrupters (GFCI""s), arc fault circuit interrupters, immersion detection circuit interrupters, appliance leakage circuit interrupters, circuit breakers, contactors, latching relays and solenoid mechanisms. More particularly, the present invention relates to a method and apparatus for resetting and testing such devices which are capable of being xe2x80x9clocked outxe2x80x9d such that the device cannot be reset if the device becomes non-operational or if an open neutral condition exists.
2. Description of Related Art
The electrical wiring device industry has witnessed an increasing need for circuit breaking devices which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters. Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894 (the xe2x80x9c""894 patentxe2x80x9d) use a trip mechanism to mechanically break an electrical connection between one or more input and output conductors. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device of the ""894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the connection between input and output conductors) includes a solenoid or trip coil. A test button is used to test the trip mechanism and circuitry used to test for faults, and a reset button is used to reset the electrical connection between input and output conductors.
However, instances may arise where an abnormal condition, caused by, for example, a lightening strike occurs which may result not only in a surge of electricity at the device but also a disabling of the trip mechanism used to cause the mechanical breaking of the circuit. This may occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (verses load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, current GFCI devices which have tripped, may be reset even though the open neutral condition may remain.
The device described in commonly owned U.S. Pat. No. 6,040,967, (""967) relates to resettable circuit interrupting devices, such as but not limited to GFCI devices, that include a reset lock-out mechanism which prevents the resetting of electrical connections or continuity between input and output conductors if the circuit interrupter used to break the connection is non-operational or if an open neutral condition exists. In this device, both the test button used to test the trip mechanism and circuitry used to sense faults, and the reset button used to reset the electrical connection between input and output conductors requires electrical power to operate an electrical component. A GFCI that can be tripped manually without requiring electrical power is desirable.
The present application relates to resettable circuit interrupting devices, such as, but not limited to, GFCI devices, that include a reset lock-out mechanism which prevents the resetting of electrical connections between input and output conductors if the circuit interrupter used to break the connection is non-operational or if an open neutral condition exists. The circuit interrupter includes a trip mechanism used to cause the breaking of continuity between the input and output conductive paths or conductors and the sensing circuit used to sense faults.
In one embodiment, the circuit interrupting device includes a housing, an input conductive path and an output conductive path. The input conductive path is disposed at least partially within the housing and is capable of being electrically connected to a source of electricity. The output conductive path is also disposed at least partially within the housing and is capable of conducting electrical current to a load when electrical continuity is established with the input conductive path. Electrical continuity between the conductive paths may be established using electromechanical mechanisms, such as movable electrical contacts and solenoids. The device also includes a circuit interrupted disposed within the housing and configured to break electrical continuity between the input and output conductive paths in response to the occurrence of a predetermined condition. Predetermined conditions include, without limitation, ground faults, arc faults, appliance leakage faults and immersion faults.
In response to the occurrence of the predetermined condition, a reset lock-out operable in a lock-out position and in a reset position is set to one of the positions. In the lock-out position, the reset lock-out inhibits resetting of electrical continuity between the input and output conductive paths, and in the reset position, the reset lock-out does not inhibit resetting of electrical continuity between the input and output conductive paths. The circuit interrupting device includes a reset mechanism operatively associated with the reset lock-out and the circuit interrupter. Activation of the reset mechanism activates the circuit interrupter which facilitates changing the operable position of the reset lock-out from the lock-out position to the reset position.
The circuit interrupter includes what is referred to synonymously herein as either a test or trip button for disconnecting a load from a source of electrical power and a reset button for resetting the device after it has tripped. When the device is operating in its reset state, a source of electrical power is connected to a load through a set of contacts located within the device. The contacts are held closed by the spring loaded reset button which holds captive a latch plate that urges the normally open contacts to a closed condition. In the preferred mechanical trip mechanism, depressing the trip button causes the latch plate to move forward to be released from the reset button. The latch plate, upon being released from the reset button moves down as a result of leaf spring downward biasing thereof to allow the contacts, which are biased as a result of this downward biasing to be normally open, to assume that normally open position. At this time, pressing the reset button initiates an electrical cycle which causes the normally open contacts to close only if the device is operating properly and there is no fault on the line. The device described is mechanically tripped, and both mechanically and electrically reset, and it can be tripped without power being supplied to the device.
The foregoing has outlined, rather broadly, the preferred feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention and that such other structures do not depart form the spirit and scope of the invention in its broadest form.